Betaine is a valuable compound which is used in animal fodders, as well as in pharmaceutical and cosmetic applications.
Betaine occurs in the roots, seeds and stems of a great variety of plants. Its concentration in sugar beet is relatively high, 1.0% to 1.5% on a dry solids basis. When sugar beet is processed for the recovery of sucrose, betaine concentrates in the molasses. Beet molasses usually contains from 3% to 8% of betaine calculated on a dry solids basis.
Betaine is an amphoteric compound having the formula:(H3C)3N+—CH2—COO−
It is known in the art to recover betaine from beet molasses, rest molasses or vinasse by ion exchange, by crystallization as a hydrochloride, by extraction with an organic solvent, or by chromatography.
A chromatographic method for the recovery of betaine from beet molasses is decribed in U.S. Pat. No. 4,359,430 (Suomen Sokeri Oy). This method is a chromatographic process in which molasses which contains betaine, such as beet molasses, is introduced to the top of a column containing a polystyrene sulphonate cation exchange resin, typically in an alkali metal form. Elution with water is carried out for the recovery of betaine, sucrose and residual molasses from the downstream side of the resin bed.
Another process for the recovery of betaine from molasses has been described in U.S. Pat. No. 5,127,957 (Heikkilä et al.) using a chromatographic simulated moving bed system having at least three chromatographic columns connected in series. Betaine and sucrose are recovered as separate product fractions during the same cycle of the chromatographic simulated moving bed system. The columns of the chromatographic system are typically filled with a strong acid cation exchange resin in a monovalent ion form, preferably in sodium and/or potassium form.
A further process for the fractionation of molasses has been disclosed in U.S. Pat. No. 6,093,326 (Danisco Finland Oy). In this process, at least one product fraction is recovered during a multi-step sequence in two or more loops in a chromatographic simulated moving bed system. One embodiment of the process relates to a method of separating sucrose and betaine from molasses to recover a sucrose fraction and a betaine fraction. The chromatographic system comprises at least two partial packing material beds. The filling material of the columns is typically a strong acid, gel-type cation exchange resin in a monovalent ion form, preferably in sodium and/or potassium form.
WO 96/10650 (Cultor Oy) relates to a method for separating sucrose and additionally a second component, such as betaine, from a beet-derived sucrose-containing solution. The process comprises subjecting the solution to two successive chromatographic fractionations with a simulated moving bed method to yield one or more fractions enriched in sucrose and a fraction enriched in said second component. The chromatographic separation is typically carried out with a strong acid cation exchanger in sodium and/or potassium form.
DE-OS 2 362 211 (Süddeutsche Zucker AG) discloses a chromatographic separation process for separating molasses into a sugar fraction and a non-sugar fraction using a cation exchange resin in Ca2+ form. The process has the disadvantage that the Ca2+ form of the resin is not in equilibrium with the cation composition of the mobile phase.
U.S. Pat. No. 4,333,770 (UOP Inc.) discloses a process for separating sucrose from an aqueous mixture of a sugar source, such as molasses, by contacting said mixture with an adsorbent consisting of a carbonaceous pyropolymer. The process separates betaine from salts poorly. U.S. Pat. No. 4,405,377 (UOP Inc.) discloses a process for the separation of monosaccharides from a feed mixture comprising an aqueous solution of monosaccharides by contacting said solution with an adsorbent comprising crystalline aluminosilicate, such as zeolite. The feed mixture is diluted with ethanol before the adsorbent treatment. The feed mixture may be a starch syrup, such as corn syrup, for example. This process is not used for the separation of betaine. U.S. Pat. No. 4,405,378 (UOP Inc.) discloses a process for separating sucrose from an aqueous solution containing sucrose, betaine and/or mineral salts by contacting said solution with an adsorbent comprising activated carbon powder bound with an organic polymer (a cellulose nitrate, a cellulose ester or a mixture thereof). This process separates betaine from salts poorly.
U.S. Pat. No. 6,379,554 (Amalgamated Research Inc.) discloses a system where a plurality of chromatographic separation operations, including a first simulated moving bed operation, are coupled into a process which functions, preferably through the application of continuous displacement chromatography, to recover a fraction rich in small organic molecules, notably betaine and/or invert sugar from sucrose solutions, enabling the subsequent production of a high purity sucrose product.
EP 0 411780 (Kampen Willem Hemmo) discloses a process for the recovery of betaine from beet stillage produced from the fermentation and distillation of sugar beets. The process comprises the steps of a) clarifying the stillage product by using a cross-flow micro-filtration process with inorganic membranes having a pore size in the range of 0.1. to 10 μm to remove the solid substances and (b) subjecting the clarified stillage to chromatographic separation by ion exclusion for separating betaine. The chromatographic separation by ion exclusion may be carried out with a suitable resin material, such as SM-51-Na resin (IWT), IWT-AM-63 or DOWEX 50-WX8 (Dow Chemical). Other products, such as ethanol, glycerol, succinic acid, lactic acid, potassium sulphate and L-pyroglutamic acid may be recovered in the process, in addition to betaine.
Nanofiltration is a relatively new pressure-driven membrane filtration process for the separation of soluble components of the nanofiltration feed, falling between reverse osmosis and ultrafiltration. Nanofiltration typically retains divalent salts and organic molecules with a molar mass greater than 300 g/mol. The most important nanofiltration membranes are composite membranes made by interfacial polymerisation. Polyether sulfone membranes, sulfonated polyether sulfone membranes, polyester membranes, polysulfone membranes, aromatic polyamide membranes, polyvinyl alcohol membranes and polypiperazine membranes are examples of widely used nanofiltration membranes. Inorganic and ceramic membranes can also be used for nanofiltration.
It is known in the art to use nanofiltration for separating glucose from disaccharides and higher saccharides. The starting mixture including glucose may be a starch hydrolysate, for example. One process for separating glucose from disaccharides and higher saccharides by nanofiltration has been disclosed in WO 99/28490 (Novo Nordisk), for example.
U.S. Pat. No. 4,511,654 (UOP Inc.) relates to a process for the production of a high glucose or maltose syrup by treating a glucose/maltose-containing feedstock With an enzyme selected from amyloglucosidase and β-amylase to form a partially hydrolyzed reaction mixture, passing the resultant partially hydrolyzed reaction mixture through an ultrafiltration membrane to form a retentate and a permeate, recycling the retentate to the enzyme treatment stage, and recovering the permeate including the high glucose or maltose syrup.
WO 01/14594 A2 (Tate & Lyle Inc.) discloses a sugar beet membrane filtration process for producing sucrose from a sugar beet pulp. The membrane filtration can be done with an ultrafiltration membrane or a nanofiltration membrane, for example. In one embodiment of said process, the membrane filtration is carried out using two successive ultrafiltration steps optionally combined with diafiltration, followed by a nanofiltration step, thereby producing a nanofiltration permeate and a nanofiltration retentate. The nanofiltration retentate contains most of the sucrose from the beets. In a preferred embodiment of the process, the nanofiltration retentate contains at least about 89 to 91% by weight of sucrose (on dry substance basis). The nanofiltration permeate, on the other hand, is recited to contain at least about 25 to 50% of the betaine present in the nanofiltration feed. Loose nanofiltration membranes with NaCl rejection of about 10% are recited to be well suited for the nanofiltration step.
The above-mentioned reference WO 01/14594 A2 also proposes chromatographic separation for further purification of the sucrose-containing retentate obtained from the ultrafiltration/diafiltration. A purified sucrose fraction is thus obtained.
However, a combination of chromatography and nanofiltration to recover betaine from sugar beet-derived solutions have not been disclosed or suggested in the state of the art.